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H. N.. I. A. & 0. MERWIN.

TUBULAR BOILER.

No. 366,234. I Patented July 12, 1887.

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UNITED STATES PATENT OFFICE.

HARLEY N. MERVVIN, IRVING A. MERIVIN, AND OLIVER MERIVIN, OF

' IROQUOIS, DAKOTA TERRITORY.

TUBULAR BOILER.

SPECIFICATION formin part of Letters Patent No. 366,234, dated July 12,.188'7. Application filed March 3|, 1857. Serial No. 233,103. (No model.)

To all whom it may concern:

Be it known that we, HARLEY N. MERWIN, IRVING A. MERwrN, and OLIVER MERWIN, citizens of the United States, residing at Iroquois, in the county of Kingsbury, Dakota Territory, have invented a new and useful Improvement in Tubular Boilers, of which the following is a specification.

The invention relates to improvements in tubular-boilers, referring more particularly to the tubes or fines therein; and it consists in the combination and arrangement of the said fines and the method of securing the ends of the same to the line-plates, as hereinafter described, illustrated in the drawings, and pointed out in the appended claim.

In the accompanying drawings, Figure 1 represents a vertical longitudinal section of a boiler embodying the invention. Fig. 2 is a side View of one of the tubes or flues en- Fig. 3 is a central longitudinal section of the same. Fig. 4 is a side view of two or more flues secured at their ends to the flueplates. Figs. 5 and 6, respectively, represent views of the front and rear flue-plates.

Referring to the drawings by letter, A rep resents a boiler, of which B is the smokebox, G the SIDOkB'SlJZLCk, and D the fire-box, the shell of the boiler being designated by .a, and the flue-plates by E E and F F, the former adjacentto the smoke-box and the latter to the fire-box.

G G are thellues larger at their front ends, H, than at their rear ends, I, but having threads at each end of the same pitch or cut by the same screw-plate. The openings e in the front flue-plates are as much larger than those, f, in

the rear flue-plates as the points'of the lines that screw in the former are larger than the points screwing into the latter, and the fines are snfliciently smaller at their rear or inner ends to be passed through the corresponding openings, 0 e, in the larger flue-plates until their inner ends reach the openings in the rear flue-plates. The dues are then screwed simultaneously into the front and rear plates, So that much time and labor issaved in fitting the parts together, and the parts connect snugly when so fitted. The flues, when con nected by the described method, can be fitted very tightly, so as not to be liable to leakage. Before screwing the ends into the line-plates the said ends are covered with fire-proofpaint to more certainly prevent any leakage.

Having thus explained our invention, we clain1- The combination,with the plates E and F, of i a boiler-tube, G, having the screw threaded end I engaging with the plate E, and the internally-enlarged screw-threaded end H increased in diameter only at the point which enters the aperture in the plate F without increasing the diaincter of the main body ofthe tube, substantially as described.

In testimony that we claim the foregoing as our own we have hereto affixed oursignatures in presence of two witnesses.

Witnesses:

A. I. SCHENIAN, ED. MoRosTIE. 

